Graduate Defense: Ruchi Shrestha

Thesis Information

Title: Study Of Dry Mixing Method To Apply Microbial-Induced Calcite Precipitation For Soil Treatment

Program: Master of Science in Civil Engineering

Advisor: Dr. Bhaskar Chittoori, Civil Engineering

Committee Members: Dr. Nick Hudyma (Co-Chair), Civil Engineering; and Michael Dickey, Civil Engineering

Abstract

Microbially Induced Calcite Precipitation (MICP) has gained recognition as a promising technique for soil stabilization, involving the binding of soil particles, formation of calcium carbonate (CaCO3) coating, and reduction of void space. MICP through biostimulation utilizes the bacteria of soil to trigger calcite precipitation through ureolysis. The conventional approach of applying MICP through biostimulation requires the preparation and injection of treatment solutions in different phases, yet it faces challenges such as clogging, uneven distribution of calcite, equipment requirements, and high costs.

This study investigates an alternative method for applying MICP through biostimulation by directly blending dry chemical compounds into the soil and subsequently adding water. This approach offers potential advantages in terms of convenience, ease of implementation, and cost-effectiveness, as it eliminates the need to prepare and mix treatment solutions, streamlining the application process for large-scale implementation.

Three dry protocols were developed and applied to various soil samples in this research. The results obtained were then compared with those achieved using the conventional protocol. The findings demonstrated that the dry mixing protocols resulted in significant calcium carbonate precipitation, comparable to or even surpassing the conventional protocol after multiple treatment rounds. This study widens the possibilities and serves as an initial step in providing valuable insights into the feasibility of utilizing dry mixing methods for MICP in soil stabilization.